The purpose of an instant bingo card or ticket is to simulate the play of a conventional bingo game utilizing instant lottery technology. An instant bingo card will normally include a caller card portion which has a number of combinations of letters and numbers covered by a latex or scratch-off coating. The letter-number combinations on the caller's card correspond to the letter-number combinations found on the balls that are typically drawn in a conventional bingo game. There are normally twenty five letter-number combination printed under the scratch-off coating. Also printed on an instant bingo card is a group of usually four to six player cards which are similar in format to bingo cards used by players in conventional bingo games. To play the game, a player will scratch off the coating over the letter-number combinations on the caller's card and mark on each of the player cards any numbers that may correspond to letter-number combinations on the caller's card. Usually printed on the instant bingo card adjacent to the player cards is an indication of the combinations that will result in the awarding of a prize. After marking the player cards, the player is able to determine if one or more of the player cards represent a winning combination and if a winning combination is present, the player can then present the card to a lottery agent to redeem the indicated prize(s).
One of the challenges of producing a commercially satisfactory instant lottery card is to provide a method for marking the player cards which is convenient to use yet economical to manufacture. In one approach the numbers on the player cards are covered by a scratch-off coating and numbers corresponding directly to the numbers printed on the player card are printed, utilizing for example a technique disclosed in U.S. Pat. No. 5,074,566, on the scratch-off coating. The player is, then able to mark his cards by scratching off the numbers on his player card corresponding to the letter-number combinations on the caller card portion of the instant bingo card. This approach has two disadvantage in that it requires a second scratch-off area and more importantly requires two separate printings of the numbers on the player cards. These factors substantially increase the manufacturing cost of the card. The second scratch-off area also results in a great deal more scratch-off debris following the play of the game.
A second technique, as disclosed in U.S. Pat. No. 5,193,815, is to print a translucent coat of a scratchable material over the player cards which is pigmented so as to modify the appearance of the color of the area under the translucent coat. By scratching off the translucent coat over a particular number on the player cards, the player can mark this number by the resulting apparent color change. This approach has three disadvantages. First, when effecting the color change the player's card area always changes from a darker color to a lighter color. This is the opposite of how a player marks his card in an actual bingo game. Second, the color(s) of the player's cards before rubbing (marking) are always created colors. The created color(s) are the combination of the color of the underlying layer on which the player's numbers are printed and the color of the translucent tinted layer. Colors created in this fashion are limited by the tint of the scratch-off translucent layer. The color of the translucent layer is limited in that it must be of sufficient contrast to result in easily discernible marks of the player's card when removed but not so dark as to make reading of the player's number difficult prior to removal. Finally, the scratch-off layer over the player's cards results in more scratch-off debris following play of the game.